Add POTE app project support and improve IP conflict detection

- Add roles/pote: Python/venv deployment role with PostgreSQL, cron jobs
- Add playbooks/app/: Proxmox app stack provisioning and configuration
- Add roles/app_setup: Generic app deployment role (Node.js/systemd)
- Add roles/base_os: Base OS hardening role
- Enhance roles/proxmox_vm: Split LXC/KVM tasks, improve error handling
- Add IP uniqueness validation: Preflight check for duplicate IPs within projects
- Add Proxmox-side IP conflict detection: Check existing LXC net0 configs
- Update inventories/production/group_vars/all/main.yml: Add pote project config
- Add vault.example.yml: Template for POTE secrets (git key, DB, SMTP)
- Update .gitignore: Exclude deploy keys, backup files, and other secrets
- Update documentation: README, role docs, execution flow guides

Security:
- All secrets stored in encrypted vault.yml (never committed in plaintext)
- Deploy keys excluded via .gitignore
- IP conflict guardrails prevent accidental duplicate IP assignments

README.md

@@ -35,10 +35,8 @@ Other useful entry points:
 
 Safety notes:
 
-- **IP conflict precheck**: provisioning fails if the target IP responds
-  (override with `-e allow_ip_conflicts=true` only if you really mean it).
-- **VMID/CTID collision guardrail**: provisioning fails if the VMID exists but the guest name doesn't match
-  (override with `-e allow_vmid_collision=true` only if you really mean it).
+- **IP conflict precheck**: provisioning fails if the target IP responds (override with `-e allow_ip_conflicts=true` only if you really mean it).
+- **VMID/CTID collision guardrail**: provisioning fails if the VMID exists but the guest name doesn’t match (override with `-e allow_vmid_collision=true` only if you really mean it).
 - **No destructive playbooks**: this repo intentionally does **not** ship “destroy/decommission” automation.
 
 Docs: